RIYADH (Reuters) - Britain and Saudi Arabia signed a framework deal on military and security cooperation, Saudi state news agency SPA said on Tuesday, redoubling efforts to counter Iran in the Gulf region and defeat Islamic State.

Prime Minister Theresa May said in December that Britain would invest over 3 billion pounds ($4.05 billion) in defense in Gulf Arab states over the next decade as it seeks to build on traditionally strong ties with the conservative, oil-wealthy monarchies before its planned departure from the European Union.

British Defence Secretary Michael Fallon discussed military cooperation with Crown Prince Mohammed bin Salman, who serves as the kingdom’s defense minister and deputy prime minister, the SPA report said without providing details of the agreement.

Gulf Arab states say Iran is trying to expand its influence in Arab countries, including Syria, Iraq and Yemen. Since March 2015, Saudi Arabia and Arab allies have been waging war against Iran-aligned Houthi forces that seized control of much of Yemen.

Britain’s close relationship with Gulf states has drawn concern from human rights groups, including criticism of Saudi air strikes in Yemen’s war that have killed hundreds of civilians. British military personnel have been working with the Saudi forces.